﻿using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.IO;

namespace testingIO
{
    	/*

	   Porter stemmer in CSharp, based on the Java port. The original paper is in

		   Porter, 1980, An algorithm for suffix stripping, Program, Vol. 14,
		   no. 3, pp 130-137,

	   See also http://www.tartarus.org/~martin/PorterStemmer

	   History:

	   Release 1

	   Bug 1 (reported by Gonzalo Parra 16/10/99) fixed as marked below.
	   The words 'aed', 'eed', 'oed' leave k at 'a' for step 3, and b[k-1]
	   is then out outside the bounds of b.

	   Release 2

	   Similarly,

	   Bug 2 (reported by Steve Dyrdahl 22/2/00) fixed as marked below.
	   'ion' by itself leaves j = -1 in the test for 'ion' in step 5, and
	   b[j] is then outside the bounds of b.

	   Release 3

	   Considerably revised 4/9/00 in the light of many helpful suggestions
	   from Brian Goetz of Quiotix Corporation (brian@quiotix.com).

	   Release 4

	*/

	/**
	  * Stemmer, implementing the Porter Stemming Algorithm
	  *
	  * The Stemmer class transforms a word into its root form.  The input
	  * word can be provided a character at time (by calling add()), or at once
	  * by calling one of the various stem(something) methods.
	  */

	class Stemmer {
		private char[] b;
		private int i,     /* offset into b */
			i_end, /* offset to end of stemmed word */
			j, k;
		private static int INC = 50;
		/* unit of size whereby b is increased */
		
		public Stemmer() {
			b = new char[INC];
			i = 0;
			i_end = 0;
		}

        public string stem(string s)
        {
            i = s.Length;
            char[] new_b = new char[i];
            for (int c = 0; c < i; c++)
                new_b[c] = s[c];

            b = new_b;
            stem();
            return new String(b, 0, i_end);
        }

		/**
		 * Add a character to the word being stemmed.  When you are finished
		 * adding characters, you can call stem(void) to stem the word.
		 */

		public void add(char ch) {
			if (i == b.Length) {
				char[] new_b = new char[i+INC];
				for (int c = 0; c < i; c++)
					new_b[c] = b[c];
				b = new_b;
			}
			b[i++] = ch;
		}


		/** Adds wLen characters to the word being stemmed contained in a portion
		 * of a char[] array. This is like repeated calls of add(char ch), but
		 * faster.
		 */

		public void add(char[] w, int wLen) {
			if (i+wLen >= b.Length) {
				char[] new_b = new char[i+wLen+INC];
				for (int c = 0; c < i; c++)
					new_b[c] = b[c];
				b = new_b;
			}
			for (int c = 0; c < wLen; c++)
				b[i++] = w[c];
		}

		/**
		 * After a word has been stemmed, it can be retrieved by toString(),
		 * or a reference to the internal buffer can be retrieved by getResultBuffer
		 * and getResultLength (which is generally more efficient.)
		 */
		public override string ToString() {
			return new String(b,0,i_end);
		}

		/**
		 * Returns the length of the word resulting from the stemming process.
		 */
		public int getResultLength() {
			return i_end;
		}

		/**
		 * Returns a reference to a character buffer containing the results of
		 * the stemming process.  You also need to consult getResultLength()
		 * to determine the length of the result.
		 */
		public char[] getResultBuffer() {
			return b;
		}

		/* cons(i) is true <=> b[i] is a consonant. */
		private bool cons(int i) {
			switch (b[i]) {
				case 'a': case 'e': case 'i': case 'o': case 'u': return false;
				case 'y': return (i==0) ? true : !cons(i-1);
				default: return true;
			}
		}

		/* m() measures the number of consonant sequences between 0 and j. if c is
		   a consonant sequence and v a vowel sequence, and <..> indicates arbitrary
		   presence,

			  <c><v>       gives 0
			  <c>vc<v>     gives 1
			  <c>vcvc<v>   gives 2
			  <c>vcvcvc<v> gives 3
			  ....
		*/
		private int m() {
			int n = 0;
			int i = 0;
			while(true) {
				if (i > j) return n;
				if (! cons(i)) break; i++;
			}
			i++;
			while(true) {
				while(true) {
					if (i > j) return n;
					if (cons(i)) break;
					i++;
				}
				i++;
				n++;
				while(true) {
					if (i > j) return n;
					if (! cons(i)) break;
					i++;
				}
				i++;
			}
		}

		/* vowelinstem() is true <=> 0,...j contains a vowel */
		private bool vowelinstem() {
			int i;
			for (i = 0; i <= j; i++)
				if (! cons(i))
					return true;
			return false;
		}

		/* doublec(j) is true <=> j,(j-1) contain a double consonant. */
		private bool doublec(int j) {
			if (j < 1)
				return false;
			if (b[j] != b[j-1])
				return false;
			return cons(j);
		}

		/* cvc(i) is true <=> i-2,i-1,i has the form consonant - vowel - consonant
		   and also if the second c is not w,x or y. this is used when trying to
		   restore an e at the end of a short word. e.g.

			  cav(e), lov(e), hop(e), crim(e), but
			  snow, box, tray.

		*/
		private bool cvc(int i) {
			if (i < 2 || !cons(i) || cons(i-1) || !cons(i-2))
				return false;
			int ch = b[i];
			if (ch == 'w' || ch == 'x' || ch == 'y')
				return false;
			return true;
		}

		private bool ends(String s) {
			int l = s.Length;
			int o = k-l+1;
			if (o < 0)
				return false;
			char[] sc = s.ToCharArray();
			for (int i = 0; i < l; i++)
				if (b[o+i] != sc[i])
					return false;
			j = k-l;
			return true;
		}

		/* setto(s) sets (j+1),...k to the characters in the string s, readjusting
		   k. */
		private void setto(String s) {
			int l = s.Length;
			int o = j+1;
			char[] sc = s.ToCharArray();
			for (int i = 0; i < l; i++)
				b[o+i] = sc[i];
			k = j+l;
		}

		/* r(s) is used further down. */
		private void r(String s) {
			if (m() > 0)
				setto(s);
		}

		/* step1() gets rid of plurals and -ed or -ing. e.g.
			   caresses  ->  caress
			   ponies    ->  poni
			   ties      ->  ti
			   caress    ->  caress
			   cats      ->  cat

			   feed      ->  feed
			   agreed    ->  agree
			   disabled  ->  disable

			   matting   ->  mat
			   mating    ->  mate
			   meeting   ->  meet
			   milling   ->  mill
			   messing   ->  mess

			   meetings  ->  meet

		*/

		private void step1() {
			if (b[k] == 's') {
				if (ends("sses"))
					k -= 2;
				else if (ends("ies"))
					setto("i");
				else if (b[k-1] != 's')
					k--;
			}
			if (ends("eed")) {
				if (m() > 0)
					k--;
			} else if ((ends("ed") || ends("ing")) && vowelinstem()) {
				k = j;
				if (ends("at"))
					setto("ate");
				else if (ends("bl"))
					setto("ble");
				else if (ends("iz"))
					setto("ize");
				else if (doublec(k)) {
					k--;
					int ch = b[k];
					if (ch == 'l' || ch == 's' || ch == 'z')
						k++;
				}
				else if (m() == 1 && cvc(k)) setto("e");
			}
		}

		/* step2() turns terminal y to i when there is another vowel in the stem. */
		private void step2() {
			if (ends("y") && vowelinstem())
				b[k] = 'i';
		}

		/* step3() maps double suffices to single ones. so -ization ( = -ize plus
		   -ation) maps to -ize etc. note that the string before the suffix must give
		   m() > 0. */
		private void step3() {
			if (k == 0)
				return;
			
			/* For Bug 1 */
			switch (b[k-1]) {
				case 'a':
					if (ends("ational")) { r("ate"); break; }
					if (ends("tional")) { r("tion"); break; }
					break;
				case 'c':
					if (ends("enci")) { r("ence"); break; }
					if (ends("anci")) { r("ance"); break; }
					break;
				case 'e':
					if (ends("izer")) { r("ize"); break; }
					break;
				case 'l':
					if (ends("bli")) { r("ble"); break; }
					if (ends("alli")) { r("al"); break; }
					if (ends("entli")) { r("ent"); break; }
					if (ends("eli")) { r("e"); break; }
					if (ends("ousli")) { r("ous"); break; }
					break;
				case 'o':
					if (ends("ization")) { r("ize"); break; }
					if (ends("ation")) { r("ate"); break; }
					if (ends("ator")) { r("ate"); break; }
					break;
				case 's':
					if (ends("alism")) { r("al"); break; }
					if (ends("iveness")) { r("ive"); break; }
					if (ends("fulness")) { r("ful"); break; }
					if (ends("ousness")) { r("ous"); break; }
					break;
				case 't':
					if (ends("aliti")) { r("al"); break; }
					if (ends("iviti")) { r("ive"); break; }
					if (ends("biliti")) { r("ble"); break; }
					break;
				case 'g':
					if (ends("logi")) { r("log"); break; }
					break;
				default :
					break;
			}
		}

		/* step4() deals with -ic-, -full, -ness etc. similar strategy to step3. */
		private void step4() {
			switch (b[k]) {
				case 'e':
					if (ends("icate")) { r("ic"); break; }
					if (ends("ative")) { r(""); break; }
					if (ends("alize")) { r("al"); break; }
					break;
				case 'i':
					if (ends("iciti")) { r("ic"); break; }
					break;
				case 'l':
					if (ends("ical")) { r("ic"); break; }
					if (ends("ful")) { r(""); break; }
					break;
				case 's':
					if (ends("ness")) { r(""); break; }
					break;
			}
		}

		/* step5() takes off -ant, -ence etc., in context <c>vcvc<v>. */
		private void step5() {
			if (k == 0)
				return;

			/* for Bug 1 */
			switch ( b[k-1] ) {
				case 'a':
					if (ends("al")) break; return;
				case 'c':
					if (ends("ance")) break;
					if (ends("ence")) break; return;
				case 'e':
					if (ends("er")) break; return;
				case 'i':
					if (ends("ic")) break; return;
				case 'l':
					if (ends("able")) break;
					if (ends("ible")) break; return;
				case 'n':
					if (ends("ant")) break;
					if (ends("ement")) break;
					if (ends("ment")) break;
					/* element etc. not stripped before the m */
					if (ends("ent")) break; return;
				case 'o':
					if (ends("ion") && j >= 0 && (b[j] == 's' || b[j] == 't')) break;
					/* j >= 0 fixes Bug 2 */
					if (ends("ou")) break; return;
					/* takes care of -ous */
				case 's':
					if (ends("ism")) break; return;
				case 't':
					if (ends("ate")) break;
					if (ends("iti")) break; return;
				case 'u':
					if (ends("ous")) break; return;
				case 'v':
					if (ends("ive")) break; return;
				case 'z':
					if (ends("ize")) break; return;
				default:
					return;
			}
			if (m() > 1)
				k = j;
		}

		/* step6() removes a final -e if m() > 1. */
		private void step6() {
			j = k;
			
			if (b[k] == 'e') {
				int a = m();
				if (a > 1 || a == 1 && !cvc(k-1))
					k--;
			}
			if (b[k] == 'l' && doublec(k) && m() > 1)
				k--;
		}

		/** Stem the word placed into the Stemmer buffer through calls to add().
		 * Returns true if the stemming process resulted in a word different
		 * from the input.  You can retrieve the result with
		 * getResultLength()/getResultBuffer() or toString().
		 */
		public void stem() {
			k = i - 1;
			if (k > 1) {
				step1();
				step2();
				step3();
				step4();
				step5();
				step6();
			}
			i_end = k+1;
			i = 0;
		}

		/** Test program for demonstrating the Stemmer.  It reads text from a
		 * a list of files, stems each word, and writes the result to standard
		 * output. Note that the word stemmed is expected to be in lower case:
		 * forcing lower case must be done outside the Stemmer class.
		 * Usage: Stemmer file-name file-name ...
		 */
	/*	public static void Main( String[] args ) {
			if ( args.Length == 0 ) {
				Console.WriteLine( "Usage:  Stemmer <input file>" );
				return;
			}
			char[] w = new char[501];
			Stemmer s = new Stemmer();
			for (int i = 0; i < args.Length; i++)
				try {
					FileStream _in = new FileStream( args[i], FileMode.Open, FileAccess.Read );
					try {
						while(true) {
							int ch = _in.ReadByte();
							if ( Char.IsLetter((char) ch)) {
								int j = 0;
								while(true) {
									ch = Char.ToLower((char) ch);
									w[j] = (char) ch;
									if (j < 500)
										j++;
									ch = _in.ReadByte();
									if (!Char.IsLetter((char) ch)) {
										/* to test add(char ch) */
		/*								for (int c = 0; c < j; c++)
											s.add(w[c]);
										/* or, to test add(char[] w, int j) */
										/* s.add(w, j); */
			/*							s.stem();
								
										String u;

										/* and now, to test toString() : */
			/*							u = s.ToString();

										/* to test getResultBuffer(), getResultLength() : */
										/* u = new String(s.getResultBuffer(), 0, s.getResultLength()); */

				/*						Console.Write(u);
										break;
									}
								}
							}
							if (ch < 0)
								break;
							Console.Write((char)ch);
						}
					} catch (IOException ) {
						Console.WriteLine("error reading " + args[i]);
						break;
					}
				} catch (FileNotFoundException ) {
					Console.WriteLine("file " + args[i] + " not found");
					break;
				}
		}*/
	}
}



